Where is it gone ?

Sun, 10 Nov 2002 21:25:43 EST

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I think we have a math problem here.

With both capacitors in parallel the 1/2 drops off as you are using the new=20
voltage and capacitance values so 2uf * 5v^2 =3D 50uJ... No loss.

Ron West
wb4oum
---------------------------------------

In a message dated 11/8/02 1:50:07 PM Eastern Standard Time,=20
andre.kesteloot@verizon.net writes:

> Subj:Where is it gone ?=20
> Date:11/8/02 1:50:07 PM Eastern Standard Time
> From:<A HREF=3D"mailto:andre.kesteloot@verizon.net">andre.kesteloot@verizo=
n.net</A>
> Reply-to:<A HREF=3D"mailto:andre.kesteloot@ieee.org">andre.kesteloot@ieee.=
org</A>
> To:<A HREF=3D"mailto:tacos@amrad.org">tacos@amrad.org</A>
> Sent from the Internet=20
>=20
>=20
>=20
> Assume you have two identical, loss-free 1uF capacitors, one charged=20
> to 10V, the other is discharged.
>=20
> You then connect the two in parallel so the total C is now 2uF -=20
> charge will flow from the charged capacitor into the discharged
> capacitor.
>=20
> Assuming charge Q is conserved, and that Q=3DCV, the voltage must now be
> 5V.
>=20
> But the stored energy in a capacitor =3D1/2CV^2, so with the single
> charged capacitor, the stored energy is 1/2 x 1uF x 100 =3D 50uJ, while=20
> with both capacitors in parallel it is only 1/2 x 2uF x 25 =3D 25uJ.=20
> So where has the other 25uJ gone?=20
>=20
> Andr=E9
> (from the RSGB LF Reflector)
> _______________________________________________
> Tacos mailing list
> Tacos@amrad.org
> http://www.amrad.org/mailman/listinfo/tacos

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<HTML><FONT FACE=3Darial,helvetica><FONT  SIZE=3D2>I think we have a math pr=
oblem here.<BR>
<BR>
With both capacitors in parallel the 1/2 drops off as you are using the new=20=
voltage and capacitance values so 2uf * 5v^2 =3D 50uJ... No loss.<BR>
<BR>
Ron West<BR>
wb4oum<BR>
---------------------------------------<BR>
<BR>
<BR>
In a message dated 11/8/02 1:50:07 PM Eastern Standard Time, andre.kesteloot=
@verizon.net writes:<BR>
<BR>
<BR>
<BLOCKQUOTE TYPE=3DCITE style=3D"BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT=
: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Subj:<B>Where is it gone ? </B>=
<BR>
Date:11/8/02 1:50:07 PM Eastern Standard Time<BR>
From:<A HREF=3D"mailto:andre.kesteloot@verizon.net">andre.kesteloot@verizon.=
net</A><BR>
Reply-to:<A HREF=3D"mailto:andre.kesteloot@ieee.org">andre.kesteloot@ieee.or=
g</A><BR>
To:<A HREF=3D"mailto:tacos@amrad.org">tacos@amrad.org</A><BR>
<I>Sent from the Internet </I><BR>
<BR>
<BR>
<BR>
Assume you have two identical, loss-free 1uF capacitors, one charged <BR>
to 10V, the other is discharged.<BR>
<BR>
You then connect the two in parallel so the total C is now 2uF - <BR>
charge will flow from the charged capacitor into the discharged<BR>
capacitor.<BR>
<BR>
Assuming charge Q is conserved, and that Q=3DCV, the voltage must now be<BR>
5V.<BR>
<BR>
But the stored energy in a capacitor =3D1/2CV^2, so with the single<BR>
charged capacitor, the stored energy is 1/2 x 1uF x 100 =3D 50uJ, while <BR>
with both capacitors in parallel it is only 1/2 x 2uF x 25 =3D 25uJ. <BR>
So where has the other 25uJ gone? <BR>
<BR>
Andr=E9<BR>
(from the RSGB LF Reflector)<BR>
_______________________________________________<BR>
Tacos mailing list<BR>
Tacos@amrad.org<BR>
http://www.amrad.org/mailman/listinfo/tacos</BLOCKQUOTE><BR>
<BR>
</FONT></HTML>
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